Yannick Malledant

Survival, proliferation, and functions of porcine hepatocytes encapsulated in coated alginate beads : A step toward a reliable bioartificial liver

Orthotopic liver transplantation is the most effective treatment for fulminant hepatic failure. As an alternative treatment, an efficient extracorporeal bioartificial liver should contain a large yield of functional hepatocytes with an immunoprotective barrier, for providing temporary adequate metabolic support to allow spontaneous liver regeneration or for acting as a bridge toward transplantation. Survival, proliferation, and functions of porcine hepatocytes were evaluated in primary cultures and after embedding in alginate beads, which were subsequently coated with a membrane made by a transacylation reaction between propylene glycol alginate and human serum albumin. Disruption of total pig livers by collagenase perfusion/recirculation allowed the obtention of up to 10(11) hepatocytes with a viability greater than 95%. Hepatocytes in conventional cultures or embedded in coated alginate beads survived for about 10 days, secreted proteins, particularly albumin, and maintained several phase I and II enzymatic activities, namely ethoxyresorufin-O-deethylase, oxidation of nifedipine to pyridine, phenacetin deethylation to paracetamol, glucuroconjugation of paracetamol, and N-acetylation of procainamide. Typical features of mitosis and [3H]thymidine incorporation indicated that porcine hepatocytes proliferated in both conventional cultures and alginate beads. The efficacy of the membrane surrounding alginate beads for protecting cells from immunoglobulins was tested by embedding HLA-typed human lymphocytes, which were subsequently incubated with specific anti-HLA immunoglobulin G and complement. These data show that large yields of porcine hepatocytes that are embedded in coated alginate beads remain functional and are isolated from large molecular weight molecules, such as immunoglobulins. This system represents a promising tool for the design of an extracorporeal bioartificial liver, containing xenogeneic hepatocytes, to treat acute liver disease in humans.

Clinical review: The liver in sepsis

During sepsis, the liver plays a key role. It is implicated in the host response, participating in the clearance of the infectious agents/products. Sepsis also induces liver damage through hemodynamic alterations or through direct or indirect assault on the hepatocytes or through both. Accordingly, liver dysfunction induced by sepsis is recognized as one of the components that contribute to the severity of the disease. Nevertheless, the incidence of liver dysfunction remains imprecise, probably because current diagnostic tools are lacking, notably those that can detect the early liver insult. In this review, we discuss the epidemiology, diagnostic tools, and impact on outcome as well as the pathophysiological aspects, including the cellular events and clinical picture leading to liver dysfunction. Finally, therapeutic considerations with regard to the weakness of the pertinent specific approach are examined.

Diagnostic and therapeutic management of nosocomial pneumonia in surgical patients: results of the Eole study.

Objective To assess clinical, microbiological, and therapeutic features of nosocomial pneumonias in surgical patients. Design Prospective (October 1997 through May 1998), consecutive case series analysis of patients suspected of having pneumonia during the fortnight after a surgical procedure or trauma and receiving antibiotic therapy prescribed by the attending physician for this diagnosis. Setting A total of 230 study centers in teaching (n = 66) and nonteaching hospitals (n = 164) (surgical wards and intensive care units). Patients A total of 837 evaluable patients (mean age 61 ± 18 yrs) including 629 intensive care unit patients. Intervention None. Measurements and Main Results The diagnostic and therapeutic procedures followed were based on guidelines. Antibiotics and any changes of therapy and duration of treatment were decided by the attending physician. The charts were reviewed by a panel of experts that classified the cases according to clinical, radiologic, and microbiological criteria (when available). The efficacy of treatment was evaluated over a 30-day period following the index episode. The patients were classified into three groups: definite pneumonia (n = 261), possible pneumonia (n = 392), or low-probability pneumonia (n = 184). Ventilator-acquired pneumonia was reported in 303 patients. Early onset pneumonia was reported in 512 cases. Microbiological sampling was performed in 718 patients, by bronchoscopy in 367 cases, recovering 450 organisms in 328 patients, including 94 polymicrobial specimens. High proportions of Gram-negative bacteria and staphylococci were cultured, even in early onset pneumonias. Antibiotic therapy was administered for 13 ± 4 days, using monotherapy in 254 cases. Changes in the initial antibiotic therapy (135 monotherapies) were decided in 517 patients (including clinical failure or persistent infection, n = 171; organisms resistant to initial therapy, n = 177; pulmonary superinfection, n = 68). Death occurred in 180 patients, related to pneumonia in 53 cases. Conclusions Nosocomial pneumonias in surgical patients are characterized by high frequency of early onset pneumonia, high proportion of nosocomial organisms even in these early onset pneumonias, and moderate mortality rate.

Effects of epinephrine compared with the combination of dobutamine and norepinephrine on gastric perfusion in septic shock

In septic shock, the alteration of the gut barrier contributes to the development of multiple organ failure. The aim of the study was to compare epinephrine with the combination of dobutamine and norepinephrine on gastric perfusion in patients with septic shock.

Modulation of airway remodeling-associated mediators by the antifibrotic compound, pirfenidone, and the matrix metalloproteinase inhibitor, batimastat, during acute lung injury in mice

Matrix metalloproteinases (MMPs) are potent to degrade basement membrane collagen associated with acute lung injury in inflammatory processes. We have investigated effects of pirfenidone, antifibrotic agent, and batimastat, inhibitor of MMPs, on gelatinase activities, on release of tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta), as well as on recruitment of inflammatory cells in bronchoalveolar lavage (BAL) fluid after aerosol administration of lipopolysaccharide (LPS) in mice. Pretreatment with pirfenidone reduced neutrophil recruitment, TNF-alpha and TGF-beta levels, and MMP-9 secretion. In contrast, pretreatment with batimastat (30 or 60 mg/kg, i.p.) only reduced TNF-alpha and TGF-beta levels. Batimastat did not reduce MMP secretion in BAL fluid but inhibited MMP-9 activity. The increase in tissue inhibitor of matrix metalloproteinase (TIMP)-1 induced by LPS was not modified by the two drugs. These findings demonstrate that the two drugs can inhibit the in vivo increase in MMP induced by LPS, batimastat with a direct inhibitor effect on MMP activity and pirfenidone as a consequence of its antiinflammatory effect.

Clinical review: Fever in septic ICU patients - friend or foe?

In recent years, fever control in critically ill patients by medications and/or external cooling has gained widespread use, notably in patients suffering from neurological injuries. Nevertheless, such a strategy in septic patients is not supported by relevant data. Indeed, in response to sepsis, experimental and clinical studies argue that fever plays a key role in increasing the clearance of microorganisms, the immune response and the heat shock response. Moreover, fever is a cornerstone diagnostic sign in clinical practice, which aids in early and appropriate therapy, and allows physicians to follow the infection course. After discussing the physiological aspects of fever production, the present review aims to delineate the advantages and drawbacks of fever in septic patients. Finally, the treatment of fever by pharmacological and/or physical means is discussed with regards to their drawbacks, which argues for their careful use in septic patients in the absence of clinical relevance.

Estimation of the diameter and cross-sectional area of the internal jugular veins in adult patients

IntroductionUnawareness of an asymmetry between the right and left internal jugular vein (IJV) and methodological pitfalls in previous studies raise concerns about such asymmetry. Hence the aim of this prospective non-interventional study was to validate the hypothesis that right IJV diameter is greater than those of left IJV and to determine the cross-sectional area of the IJVs using computed tomography (CT)-scans and original automatic software.MethodsAll consecutive adult outpatients who underwent a thoracic contrast-enhanced (TCE) helical CT-scan during a 5-month period were included. To determine diameter and cross sectional area of the IJVs, we used Advanced Vessel Analysis software integrated in a CT-scan (Advanced Vessel Analysis on Advantage Workstation Windows 4.2; General Electrics) allowing automatic segmentation of vessels and calculation of their diameters and cross-sectional areas.ResultsA total of 360 TCE CT-scans was performed; 170 were excluded from the analysis. On the remaining 190 CT scans, the diameter and cross-sectional area of the right IJV were significantly greater than those of the left IJV (17 ± 5 mm [median: 17 mm, range: 13 to 20 mm] vs. 14 ± 5 mm [median: 13 mm, range: 10 to 16 mm], P < 0.001; and 181 ± 111 mm2 [median: 160 mm2, range: 108 to 235 mm2] vs. 120 ± 81 mm2 [median: 102 mm2, range: 63 to 168 mm2], P < 0.001, respectively).ConclusionsIn a general population of adult outpatients, the diameter and cross-sectional area of the right IJV were significantly greater than those of the left IJV. This could be an additional argument to prefer right over left IJV cannulation.

Dopexamine and norepinephrine versus epinephrine on gastric perfusion in patients with septic shock: a randomized study [NCT00134212]

IntroductionMicrocirculatory blood flow, and notably gut perfusion, is important in the development of multiple organ failure in septic shock. We compared the effects of dopexamine and norepinephrine (noradrenaline) with those of epinephrine (adrenaline) on gastric mucosal blood flow (GMBF) in patients with septic shock. The effects of these drugs on oxidative stress were also assessed.MethodsThis was a prospective randomized study performed in a surgical intensive care unit among adults fulfilling usual criteria for septic shock. Systemic and pulmonary hemodynamics, GMBF (laser-Doppler) and malondialdehyde were assessed just before catecholamine infusion (T0), as soon as mean arterial pressure (MAP) reached 70 to 80 mmHg (T1), and 2 hours (T2) and 6 hours (T3) after T1. Drugs were titrated from 0.2 μg kg-1 min-1 with 0.2 μg kg-1 min-1 increments every 3 minutes for epinephrine and norepinephrine, and from 0.5 μg kg-1 min-1 with 0.5 μg kg-1 min-1 increments every 3 minutes for dopexamine.ResultsTwenty-two patients were included (10 receiving epinephrine, 12 receiving dopexamine–norepinephrine). There was no significant difference between groups on MAP at T0, T1, T2, and T3. Heart rate and cardiac output increased significantly more with epinephrine than with dopexamine–norepinephrine, whereas. GMBF increased significantly more with dopexamine–norepinephrine than with epinephrine between T1 and T3 (median values 106, 137, 133, and 165 versus 76, 91, 90, and 125 units of relative flux at T0, T1, T2 and T3, respectively). Malondialdehyde similarly increased in both groups between T1 and T3.ConclusionIn septic shock, at doses that induced the same effect on MAP, dopexamine–norepinephrine enhanced GMBF more than epinephrine did. No difference was observed on oxidative stress.

Retrosternal bypass operation for unresectable squamous cell cancer of the esophagus

BACKGROUND A palliative bypass operation may be beneficial when severe dysphagia or tracheoesophageal fistula occurs after radiochemotherapy for unresectable tumor of the esophagus. METHODS Thirty-two patients with an unresectable tumor of the esophagus underwent a palliative retrosternal gastric (29) or colonic (3) bypass operation with ligature of the lower esophagus (3) or drainage (27). Tracheoesophageal fistula was present at operation in 20 (62.5%), including 8 after radiochemotherapy. RESULTS The overall operative mortality rate was 34.4%: 45% with tracheoesophageal fistula and 16.6% without (p < 0.01). Median intensive care and hospitalization times were 5 and 19 days, respectively. Median postoperative survival was 6 months (range, 53 to 492 days). Complications in 21 survivors were lung infections (seven), cervical fistulas (eight), and failure of the esophageal suture (two); 19 patients resumed oral nutrition, and quality of life was excellent in 6. All eight cervical fistulas regressed favorably. Postoperative radiotherapy or chemotherapy did not improve survival. CONCLUSIONS Despite the high operative mortality rate, bypass operation can provide good palliation and allow subsequent radiochemotherapy in selected patients with an unresectable tumor of the esophagus.

Inhibition of cytochrome P450 2E1 by propofol in human and porcine liver microsomes

While almost anesthetics are metabolized by the cytochrome P450 (CYP) 3A4, some major volatile ones such as halothane and sevoflurane are metabolized by CYP2E1 in humans. To determine whether 2,6-diisopropylphenol (propofol), a widely used intravenous anesthetic agent, known to inhibit CYP3A4 and CYP1A2, also inhibits CYP2E1, 6-OH hydroxylation of chlorzoxazone, a prototypical CYP2E1 substrate, was estimated using two pools of human microsomes and one pool of porcine microsomes from seven livers. Basal human enzyme activities were characterized by a V(max) of 1426+/-230 and 288+/-29 pmol min(-1)mg(-1) protein and a K(m) of 122+/-47 and 149+/-42 microM, while the corresponding porcine activities were associated with a V(max) of 352+/-42 pmol min(-1)mg(-1) protein and a K(m) of 167+/-38 microM. A competitive inhibition of CYP2E1 by propofol was observed with low inhibition constants in the therapeutic range in both porcine (19 microM) and human (48 microM) liver microsomes. These in vitro results suggest that propofol could have a protective effect on toxic metabolite activation of compounds catalyzed by CYP2E1.